Drop from _sysconfig

Author: charliermarsh

cpython-unix/build-cpython.sh

@@ -627,10 +627,14 @@ def replace_in_all(search, replace):
     replace_in_file(MAKEFILE, search, replace)
     replace_in_file(SYSCONFIGDATA, search, replace)
 
-# Replace the XCode path with a generic value.
+# Remove the Xcode path from the compiler flags.
+#
+# CPython itself will drop this from `sysconfig.get_config_var("CFLAGS")` and
+# similar calls, but _not_ if `CFLAGS` is set in the environment (regardless of
+# the `CFLAGS` value). It will almost always be wrong, so we drop it unconditionally.
 xcode_path = os.getenv("APPLE_SDK_PATH")
 if xcode_path:
-    replace_in_all(xcode_path, "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk")
+    replace_in_all("-isysroot %s" % xcode_path, "")
 
 # -fdebug-default-version is Clang only. Strip so compiling works on GCC.
 replace_in_all("-fdebug-default-version=4", "")